Piezo-based acoustic and capacitive detection

ABSTRACT

One particular implementation conforming to aspects of the present disclosure takes the form of an input device for a computing system. The input device includes a input surface on which one or more input characters are shown and one or more sensors to detect which input character is pressed or selected by the user. In one example, the input device may include one or more piezo-electric sensors that detect an acoustic pulse created when the user taps on the input surface to indicate a selected input. Each character of the input surface of the input device creates a different acoustic pulse signature when tapped such that, upon detection and receiving of the acoustic pulse at the piezo-electric sensors, the input device or computer system may compare the received pulse to a database of stored pulse signatures to determine which character on the surface of the input device was tapped by the user.

This application is a continuation of patent application Ser. No.12/690,907, filed Jan. 20, 2010, which is hereby incorporated byreferenced herein in its entirety. This application claims the benefitof and claims priority to patent application Ser. No. 12/690,907, filedJan. 20, 2010.

TECHNICAL FIELD

Embodiments relate generally to computing input devices, and morespecifically to one or more piezo-based acoustic and capacitive sensorsto detect key taps on an input device.

BACKGROUND

Many electronic devices have a keyboard or similar input device withwhich a user interacts to provide an input to an electronic or computingdevice. Most keyboards consist of an arrangement of buttons that act asmechanical buttons or switches that are pushed by the user to provideinput to the computing device. Each key of the keyboard typically has anengraved or printed character on the key that corresponds to the symbolthat is input to the computer when the particular key is pressed by theuser. In some situations, several keys may be pressed simultaneously orin sequence to produce actions or commands for the computing device.

Some keyboards and other computing input devices have done away withmechanical switches and instead employ a touch-sensitive surface input.One example of a touch-sensitive surface input device is a touch screen,such as those found at automatic teller machines (ATMs) or on personaldigital assistants (PDAs), mobile phones, tablet computing devices andother mobile computing devices. To provide an input using a touchscreen, the user presses or touches a surface with either the user'sfinger or a stylus device. The input device senses the touch, determinesits location on the touch screen and generates the corresponding input.Thus, the position of the user's finger is determined by the touchscreen and the corresponding command is inputted to the electronicdevice. Other touch-sensitive surface input devices may employ materialsother than glass, such as a metal or plastic.

In general, touch-sensitive surface or related input devices may be lessreliable in determining a pressed command or intended input whencompared with a traditional mechanical keyboard. For example, some touchscreens often require that a user tap on the screen several times beforedetecting the command. Further, touch-sensitive surface input devicesoften fail to distinguish between when a user is merely resting on thesurface of the device or actively selecting a letter or other input.

SUMMARY

One embodiment may take the form of an input device for a computingsystem. The input device may comprise a capacitive sensor configured todetect a location of an input to the input device and a piezoelectricsensor configured to detect an acoustic signature created from theinput. Further, the acoustic signature may be compared to a database ofreference acoustic signatures that indicate the location of the input tothe input device.

Another embodiment may take the form of a method for detecting an inputto an input device of a computing system. The method may comprise theoperations of receiving a first acoustic pulse at a first piezoelectricsensor and comparing the first acoustic pulse to a first databasecomprising a plurality of first reference acoustic signatures todetermine the location of the input. In addition, the method maycomprise the operations of receiving a second acoustic pulse at a secondpiezoelectric sensor and comparing the second acoustic pulse to a seconddatabase comprising a plurality of second reference acoustic signaturesto determine the location of the input.

Yet another embodiment may take the form of a computing system. Thecomputing system may comprise an input device including an input surfaceand configured to receive an input to the computing system from a userand a computer-readable storage device configured to store a database ofreference acoustic signatures. The computing system may also include acapacitive sensor configured to detect a location of the input on theinput surface and a piezoelectric sensor configured to detect the atleast one acoustic signature representing the input, such that thedetected at least one acoustic signature is compared to the database todetermine the location of the input.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a top view of an input device for a computing device.

FIG. 2 is a top view of a flat-surface keyboard input device utilizingacoustic pulse recognition to detect a tap on the surface of thekeyboard.

FIG. 3 depicts a cross-sectional view of the flat-surface keyboarddevice utilizing acoustic pulse recognition to detect a tap on thekeyboard of FIG. 2 along the line marked “AA”.

FIG. 3A depicts a cross-sectional top view of the keyboard device ofFIG. 3 along line designated “BB” that utilizes three piezo sensors310-314 to detect an acoustic pulse recognition of a tap on the keyboardsurface 302.

FIG. 4 depicts a cross-sectional view similar to that shown in FIG. 3 ofa keyboard device that utilizes a combination of piezoelectric sensorsand capacitive sensors to detect a tap on the keyboard surface.

FIG. 5 depicts a cross-sectional view similar to that shown in FIG. 3 ofa keyboard device utilizing acoustic pulse recognition to detect a tapon the keyboard, including tuning features to distort or alter theresultant acoustic signature of the tap.

FIG. 6 depicts a cross-sectional view similar to that shown in FIG. 3 ofa keyboard device utilizing acoustic pulse recognition to detect a tapon the keyboard, including openings on the surface of the keyboard todistort or alter the resultant acoustic signature of the tap.

FIG. 6A depicts a cross-sectional top view similar to that shown in FIG.3A of the keyboard device utilizing acoustic pulse recognition to detecta tap on the keyboard, including openings in the surface of the keyboardto distort or alter the resultant acoustic signature of the tap.

FIG. 7 depicts a cross-sectional view similar to that shown in FIG. 3 ofa keyboard device utilizing a combination of piezoelectric sensors todetect a tap on the keyboard surface and pressure sensors to detect adampening force applied to the device.

FIG. 7A depicts a bottom view of a keyboard device utilizing acombination of piezoelectric sensors and a pressure sensor to detect atap on the keyboard surface and a dampening force applied to the device.

FIG. 8 depicts a top view of a keyboard device utilizing a microphone tomeasure ambient noise around the keyboard to aid in detecting a tap onthe surface of the keyboard.

FIG. 9 depicts a cross-sectional view similar to that shown in FIG. 3 ofa keyboard device utilizing a combination of piezoelectric sensors andproximity sensors to detect and locate a tap on the keyboard surface.

FIG. 10 is a block diagram illustrating an exemplary device or dockingstation which may be used in implementing embodiments of the presentdisclosure.

DETAILED DESCRIPTION

One embodiment described herein takes the form of an input device for acomputing system, such as a keyboard of a computer system or a touchscreen for a mobile computing device. The input device includes an inputsurface on which one or more input characters are shown, such that auser may press or tap on the character to provide an input correspondingto that character to the computing system. The input device may alsoinclude one or more sensors to detect which input character is pressedor otherwise selected by the user. In one example, the input device mayhave one or more acoustic sensors that detect an acoustic pulse createdwhen the user taps on the input surface to indicate a selected key. Eachinput area on the surface of the input device creates a differentacoustic pulse signature when tapped, given the internal geometry andphysical characteristics of the device. Thus, upon receipt and detectionof the acoustic pulse at the acoustic sensors, the input device (orassociated computing device) may compare the received pulse to adatabase of stored pulse signatures in order to determine what segmentof the surface of the input device was tapped by the user. Suchdetection may be sufficiently precise to map the tap to a particular keyof keyboard, for example.

Several other features may be incorporated into the input device tofurther determine which segment of the input device is tapped by theuser. For example, one or more tuning features may be situated near oron the input device to alter the acoustic pulse created when aparticular segment of the input device is tapped. These tuning featuresmay create a new acoustic signature for one or more segment of the inputdevice to assist the computer system in differentiating between the tapson the segments of the input device. Additional sensors may also beincorporated to assist the computing system or input device indetermining which segment of the input device is pressed by the user.For example, a capacitive sensor may be incorporated into the inputdevice to narrow the list of possible intended segments of the inputdevice tapped by the user, as well as to determine when the user iscontinually pressing on a particular segment or otherwise maintaining aninput. One or more pressure switches and/or proximity devices may alsobe incorporated to further define the segment of the input devicepressed by the user. The pressure switches may also be used to detect adampening force present on the input device that may alter the resultantacoustic signature from a particular tap. Through these and additionalsensors, the input surface of the input device can detect and locate aninput on the surface of the device and provide a corresponding input toa computing system.

FIG. 1 depicts a top view of a mechanical-based keyboard 100 for acomputing device. As described above, the keyboard may be utilized toprovide an input to a computing system such that a user may interactwith the computing system. The keyboard 100 shown includes several keysarranged as buttons that act as mechanical buttons or switches. Each keyof the keyboard typically has an engraved or printed character on thekey that corresponds to the symbol that is input to the computer whenthe particular key is pressed by the user. As should be appreciated, forthe mechanical buttons of the keyboard 100 to operate, the buttons orkeys of the keyboard must move in a vertical manner when pressed by afinger of a user. This movement activates the button or switch below thekeys to determine which key is pressed by the user.

In some instances, an input device for a computing system made ofmechanical buttons or switches may not be feasible. For example, it maybe useful to provide an input device that is flat and has few to nomoving pieces, as this may yield a more robust product. One such deviceis a touch-based input device for a computing system. Embodiments of thepresent disclosure may take the form of such input devices.

As discussed herein, one embodiment of the present disclosure may takethe form of a flat surface input device with a keyboard interfacesimilar to that shown in FIG. 1 associated with the flat surface. FIG. 2is a top view of a flat-surface keyboard input device 200 utilizingacoustic pulse recognition to detect a tap on the surface of thekeyboard. While the embodiments described herein and throughout providefor a keyboard-type input device 200, it should be appreciated that theembodiments discussed may take any form of a input-surface input devicefor a computing system. For example, the embodiments discussed hereinmay apply to a touch-screen of a mobile device or to a tablet computingsystem. In addition, the functions of the input devices described hereinmay apply to surfaces of the input device that are not flat. Forexample, the characteristics and functions described may also beincluded in a curved surface, such as that of a mouse input device.Generally, the embodiments described may apply to any type of an inputdevice for a computing system, including but not limited to, atouch-screen, a mouse, a flat-surface keyboard, a tablet-type computingscreen, and so on. The description of the embodiments below in relationto a flat surface keyboard is for convenience only and should not beconsidered as limiting to the present disclosure.

In addition, the computing systems described herein may be any type ofcomputing or electronic device, such as a desktop computer, handheldcomputing device, personal digital assistant, mobile telephone, music oraudio player (such as an MP3 player), health or medical device,auto/vehicle-mounted device, and so on. Accordingly, a “computingdevice” or “computing system” as used encompasses all such devices andany other electronic device having a processor for performingmathematical or computational processes.

A flat surface keyboard 200 embodiment of the present disclosure maytake the form of at least one input surface 202 with some type ofindicator on the surface for each of the input characters of thekeyboard. The input surface 202 may be constructed from any solidmaterial, such as metal, glass, plastic, and so on. In a metal orplastic embodiment, the keys may be machined, stamped ormicro-perforated into the input surface 202 such that a user may pressor tap on a key to provide a corresponding input to the computingsystem. In a glass embodiment, the keys may be painted on the surface202 or provided as graphics on a display screen located below the glasssurface. Generally, the keys may include any indicator that correspondsto an input to the computing system. Further, each character may beassociated with a discrete area or segment of the input surface 202 thatthe user presses or taps to select the character for input. In theexamples discussed herein, the input surface keyboard includes anindication of a standard computer keyboard layout, including space bar,enter key, function keys, and so on.

In addition to the keyboard layout on the surface 202, the keyboard 200may also include one or more surface textures to distinguish theseparate keys of the keyboard layout. For example, the characters foreach key as well as the outline defining the key edges and other areasmay be indented into the keyboard surface 202. Generally, the keys ofthe keyboard may be finished with any surface texture that distinguishesthem to the touch of a user. Further, the flat surface keyboard 200 mayalso include a haptic or tactile feedback mechanism that is activatedwhen the user presses or taps on a key of the keyboard. In general, thehaptic response may provide a force, vibration and/or motion to theuser's fingers or hands in response to the user pressing on the keyboardsurface 202. For example, each key of the keyboard 200 may move orvibrate slightly when pressed, or when a user's finger or other objectis sensed within a certain proximity.

While the keyboard device 200 may provide a haptic response to a userinput, the flat surface keyboard typically does not include mechanicalswitches or buttons to detect the pressing of a key. Instead, the flatsurface keyboard 200 may include one or more sensors to detect when andwhere a user taps the keyboard during operation of the input device. Inone embodiment, one or more piezo-electric sensors may be utilized todetect and record an acoustic pulse created when the user taps on thekeyboard 200. FIG. 3 depicts a cross-sectional view of the flat-surfacekeyboard device utilizing acoustic pulse recognition to detect a tap onthe keyboard of FIG. 2 along the line marked “AA”. In the example shown,the keyboard 300 takes the form of a box structure with the keyboardlayout located on the top surface 302 of the box. The keyboard layoutprovides an interface to the user and maps out the particular areas ofthe surface 302 that correspond to the characters of the keyboard. Forexample, the keyboard layout may display an area defined by a squarewith a character “H” located within the square. To input the character“H” to the computing device, the user taps or presses on the areadefined by the square, similar to a mechanical-based keyboard. Ingeneral, the keyboard layout may include any number of defined inputareas and any kind of input characters.

While the keyboard shown in FIG. 3 includes a box-like structure, itshould be appreciated that the keyboard 300 may take any shape and maynot necessarily be an enclosed structure. The keyboard device is shownas a box-like structure merely for convenience herein. For example, thewalls of keyboard 300 may be curved or non-linear. In other embodiments,the keyboard device may have an input surface and one or more supportstructures or legs extending away from the input surface. In yet anotherembodiment, the keyboard device may be integrated into a computingsystem, such as a touch screen of a mobile computing device. Generally,the input device may take any shape that includes at least one surfacethat detects an input provided by a user on that surface.

In the example shown in FIG. 3, two piezo-electric (“piezo”) sensors310, 312 are arranged within the keyboard structure 300, one on the leftsidewall of the keyboard structure and the other on the right sidewallof the structure. The piezo sensors 310, 312 are situated to receive anacoustic pulse created when the user taps a segment or segments of thetop surface 302 of the keyboard device 300. While the example shownincludes two piezo sensors 310, 312, other embodiments of an inputdevice may include any number of piezo sensors. For example, FIG. 3Adepicts a cross-sectional top view of the keyboard device of FIG. 3along line “BB” that utilizes three piezo sensors 310-314 to detect anacoustic pulse recognition of a tap on the keyboard surface 302.Further, it is not required that the piezo sensors 310, 312 be locatedon the sidewalls of the keyboard; they may be located anywhere near thekeyboard in a manner such that the piezo sensors can receive theacoustic pulse that results from a tap on the surface.

While the embodiments described herein and throughout discusspiezo-electric sensors to detect the acoustic pulse resulting from a tapon the input device, it should be appreciated that the embodimentsdiscussed may include any type of sensor that detects an acousticsignal. For example, the input device 200 may incorporate one or moremicrophones to detect the acoustic signal. In other embodiments, aseismometer or an accelerometer may also be used to detect the acousticpulse created by a tap on the input device surface 202. Generally, theembodiments described may utilize any type of acoustic sensors to detectthe acoustic pulse. The description of the embodiments belowincorporating one or more piezoelectric sensors is for convenience onlyand should not be considered as limiting to the present disclosure.

During operation, a user taps on the surface 302 of the keyboard definedby the keyboard outline. For example, the user may tap on the area ofthe top surface 302 that includes an indication of the letter “H”. Whentapped, one or more acoustic pulses 304, 306 propagates away from andalong the top surface 302; these pulses originate at the point tapped.For simplicity, the acoustic pulses are shown in FIG. 3 by the arrows304, 306 propagating through the interior of the keyboard. However, itshould be appreciated that the acoustic pulses propagate away from thetap in all directions. For example, as shown in FIG. 3A, the acousticpulse may also propagate to a third piezo sensor 314 located at the backof the keyboard 300. In general, the acoustic pulse created by a tap onthe surface 302 of the keyboard device 300 is a sound wave, propagatingand reflecting off of surfaces as any sound wave typically does.

As the acoustic pulses 304, 306 propagate through the keyboard 300 andreflect off of the various edges and surfaces of the keyboard, anacoustic signature is created for the separate segments of the keyboard.The acoustic signature for a particular segment is received by the piezosensors 310, 312 and converted into an electrical signal. Thiselectrical signal may than be compared by the keyboard device 300 or anassociated computing system to a database of collected reference pulsesto determine which character input was tapped. In addition, the internalstructure of the keyboard device 300 may affect the acoustic signatureof a tap on the surface 302 of the device. The effect of the internalstructure of the keyboard 300 on the acoustic signatures is discussed inmore detail below with reference to FIG. 5.

In one example, the user may tap the area of the surface 302 of thekeyboard 300 marked as “H” to provide that character as an input to acomputing system. The tap creates an acoustic signature that is receivedat the piezo sensors 310, 312. The keyboard 300 or computing system thencompares the received signature to a database of collected acousticsignatures to determine that the received signature indicates that theuser has tapped on the keyboard surface 302 to input an “H” character.In this manner, a tap on an input surface 302 of the keyboard 300 istranslated into an input to the computing system.

The database of acoustic signatures for the keyboard device 300 to whicha received acoustic signal is compared may be collected and gathered inseveral ways. In one example, a plurality of acoustic signatures aregathered during a calibration process for the keyboard device 300.During calibration, the top surface 302 is tapped at discrete spatialintervals while the acoustic pulse received at the piezo sensors 310-314is stored. In this manner, each individual pulse signature is associatedwith a particular area or segment of the keyboard device 300. Because itis known which areas of the surface 302 of the keyboard 300 isassociated with which input character, the unique acoustic signaturesfor each input character can be stored in a database accessible by thekeyboard device 300 or computing system for comparison with the receivedsignatures during operation of the input device.

In those embodiments that incorporate a plurality of piezo sensors310-314, the received acoustic signature at each sensor may be stored inthe same or separate databases. For example, due to distance traveledand the various surface irregularities of the keyboard, the acousticpulse received at piezo sensor 314 may be different than the acousticpulse received at piezo sensor 310 for any given tap on the keyboardsurface 302. Thus, the acoustic signature for an “H” input received atpiezo sensor 312 is different from the acoustic signature for the sameinput at piezo sensor 310. As such, a separate database may bemaintained for the acoustic signatures received at each piezo sensor.Alternatively, a single database may be maintained, and each piezosensor may include a unique identifier that is used to cross-referenceentries in the database. In such an embodiment, the sensor identifierand acoustic signature may both be used to search the database formatching or similar records.

During operation, each database may be consulted to determine which areaof the surface 302 of the keyboard was tapped 300. For example, theinput device 300 or computing system may compare the received acousticpulse from a first piezo sensor 310 to a first database. This may narrowthe number of possible taps performed by a user. Once narrowed, theinput device 300 or computing system may compare the received acousticpulse from a second piezo sensor 312 to a second database to acquire anaccurate determination of the location of the user's tap to a particularinput character. As should be appreciated, several piezo sensors 310-314provide more accuracy in determining of the location of a tap on thesurface 302 of the device 300.

The input device 300 or associated computing system may perform thecomparison of the received acoustic signal to the acoustic signalsmaintained in the database in several ways. In one embodiment, thereceived acoustic signature may be compared directly to the storedacoustic signatures to determine if the received signature exactlymatches the stored signature. In another embodiment, a percentage errormay be considered such that, if the received signature does not matchthe stored signature exactly but still falls within the percentageerror, the input device 300 or computing system may determine thereceived signature matches the stored signature. In still anotherembodiment, the input device 300 or computing system may determine apeak-to-peak value for the received signature and compare that tosimilar stored peak-to-peak values. Generally, any method for comparinga received acoustic signal to a stored acoustic signal is envisioned andmay be performed by the input device 300 or associated computing system.

In addition, in those embodiments that include a plurality of piezosensors, the difference in time between when the plurality of piezosensors detect the tap may be utilized to determine the location of thetap, similar to a multilateration process. In this embodiment, the inputdevice 300 or associated computing system may use the time difference ofarrival of the acoustic pulse emitting from a tap on the surface 302 ofthe input device. By comparing the time difference of arrival at threeor more piezo sensors, the input device 300 or computing system maydetermine a location on the surface of the device that a tap occurs.Such a determination may also be used in conjunction with the comparisonof the received acoustic signatures described above to more accuratelydetermine the location of a tap.

While piezo sensors 310-314 can detect when a key is pressed or tappedby a user, the piezo-sensors alone may not be able to detect apress-and-hold action. For example, it is occasionally required duringoperation of a computing device that the user hold down a shift key orother key on the keyboard to achieve a particular input. However,because the piezo sensors 310-314 detect a pressed key based on a tap onthe surface 302 of the keyboard, holding down a key is typically notmeasured by the piezo sensors. To acquire such press-and-hold events,the keyboard device 300 may also incorporate a capacitive or other typeof sensor to detect the placement and holding of a user's finger on thesurface 302 of the device 300.

FIG. 4 depicts a cross-section view of a keyboard device 400 utilizing acombination of piezoelectric sensors 410, 412 and at least onecapacitive sensor 418 to detect a tap and press-and-hold movement on thekeyboard surface 402. The keyboard 400 and peizo sensors 410, 412 maytake the same structure and placement as described above with referenceto FIGS. 3 and 3A. In addition, one or more capacitive sensors 418 maybe located along the underside of the top surface 402 of the keyboarddevice 400 to further detect the position of a finger tap on the device,as well as detect when the user is performing a press-and-hold event ona particular key of the keyboard.

The capacitive sensor 418 may form a conductive layer located justbeneath the top surface 402 of the keyboard 400, with a small voltageapplied to the layer to create a uniform electrostatic field. Because ahuman finger may also act as a conductor, placing the finger on thesurface 402 of the keyboard 400 above the capacitive sensor 418 maycreate a distortion in the capacitive field that may be measured by thecapacitive sensor. This distortion in the capacitive field may beutilized by the keyboard device 400 to determine the location of thetouch on the surface 402. Further, as long as the user maintains contactwith the surface 402, the distortion in the capacitive field ismaintained.

In an embodiment of the input device 400 that is composed of a metal,the location of a user's finger may be detected through a capacitivesensor detecting a distortion in metal surface of the input devicesurface 402. In this example, a distortion in the surface of the metalinput device can be measured from a capacitive sensor 418 located on theinput device 400. The capacitive sensor 418 may detect a distortion inthe surface 402 of the input device 400 from the presence of a user'sinput. Thus, as the user presses on the surface of the input device 400,the capacitive sensor 418 may detect such distortion and locate suchdistortion similar as described herein.

The capacitive sensor 418 may be used in junction with the piezo sensors410, 412 to provide an accurate determination of the location of a tapby the user of the flat keyboard 400 device. For example, the piezosensors 410, 412 may be used as described above with reference to FIGS.3 and 3A to determine which area of the keyboard is tapped. However, insome instances, the exact location of the user's tap may not be obtainedthrough the piezo sensors 410, 412 alone. Rather, due to variation inthe acoustic pulse or other unforeseen events, the piezo sensors 410,412 may only be able to determine an approximate location on the surface402 of the user's tap. In this circumstance, the keyboard device 400 orassociated computing system may employ one or more capacitive sensors418 in an attempt to narrow the possible area of the user's tap to aspecific area or key. In another embodiment, the keyboard 400 orcomputing system may utilize the capacitive sensor 418 to obtain arelative area of the surface 402 that is pressed by the user and use thepiezo sensors 410, 412 to obtain the proper key. Further, a capacitivesensor 418 alone may not distinguish between an accidental touch of theinput surface and a deliberate one. However, by employing the piezosensors (which may not detect an accidental brush against the inputsurface 402), in conjunction with the capacitive sensor 418, the inputdevice 400 may detect and disregard accidental touches of the inputdevices. In this manner, the piezo sensors 410, 412 and capacitivesensors may be used in conjunction to adequately determine the key thatis pressed by the user of the keyboard device 400.

In addition, the capacitive sensor 418 may also be utilized by thekeyboard device 400 or computing system to determine when a user ispressing and holding a key down as the change in the capacitive fieldcreated by the user's finger is maintained as long as the user ispressing against the top surface 402. For example, to input capitalletters to the computing system, the user may press and hold the “shift”key of the keyboard device 400 while typing other letters on thekeyboard. However, because the piezo sensors 410, 412 detect an acousticpulse created when a user taps on the surface 402 of the input device400, the piezo sensors may only detect the first press and may notdetect the hold movement performed by the user. Because the user'sfinger continues create a change in the capacitive field of the surface402, the capacitive sensor 418 may detect the maintained presence of theuser. In this manner, the capacitive sensor 418 and piezo sensors 410,412 may be utilized in conjunction to, not only determine the locationof a keystroke on the keyboard layout, but to also detect apress-and-hold movement performed by the user.

Several other features may also be included in the keyboard device 300to further refine the determination of a location of the user's tap onthe keyboard surface 302. For example, FIG. 5 depicts a cross-sectionalview similar to that shown in FIG. 3 of a keyboard device utilizingacoustic pulse recognition to detect a tap on the keyboard, includingtuning features to distort or alter the resultant acoustic signature ofthe tap. The keyboard depicted in FIG. 5 is similar to that depictedabove in FIG. 3. However, in this embodiment, one or more tuningfeatures 520, 522 are included in the keyboard 500 to alter the acousticsignal corresponding to a tap on the surface 502.

As described above, a tap on the surface 502 of the keyboard 500 createsan acoustic pulse 504, 506 that propagates away from the tapped area.One or more piezo sensors 510, 512 located on or near the keyboardreceive the acoustic pulse. The acoustic pulse signature received byeach sensor is then compared to one or more databases to determine thearea on the surface that is tapped. The acoustic signature for anyparticular tap is created as the acoustic pulse propagates along andreflects off of surfaces of the keyboard or other surfaces near thekeyboard before reaching the piezo sensors 510, 512.

To further refine or alter the resultant acoustic pulse 504, 506 for anyparticular tap, one or more tuning features may be located between thetapped area on the surface 502 and the piezo sensors 510, 512. Thesetuning features may alter the propagation and reflection of the acousticpulse 504, 506 before it reaches the piezo sensor 510, 512, essentiallyaltering the characteristics of the acoustic pulse. Such alteration issimilar to a phase encoding of sound that occurs naturally when a soundwave enters the human ear. The keyboard 500 of FIG. 5 includes twotuning features 520, 522 that project into the keyboard structure todisrupt and alter the propagation of an acoustic pulse 504, 506resulting from tap on the surface 502. These features 520, 522 may ormay not affect the propagation of a particular tap. For example, thepropagation of acoustic pulse 506 is altered by tuning feature 522 insuch a matter that it does not reach sensor 510, while acoustic pulse504 is unaffected by tuning feature 520. Thus, the combined acousticsignature for the tap shown would be formed of the acoustic pulse 504received at piezo sensor 512 and no acoustic pulse 506 received at piezosensor 510. In reality, however, it is likely that an acoustic pulsefrom a tap on the surface 502 of the keyboard 500 will be received ateach piezo sensor 510, 512 after several reflections off of the varioussurfaces of the keyboard device.

In this manner, the acoustic signature for one or more key taps may betuned or otherwise altered by the addition or subtraction of one or moretuning features of the device. Such tuning may allow a manufacturer ofthe input device 500 to create truly unique acoustic signatures for oneor more taps on the surface 502 of the device.

In general, the keyboard device 500 may include any number and type oftuning features that alter the propagation of an acoustic pulse. Someexamples of tuning features that may alter an acoustic pulse includerough textures on the interior surface of the input device, projectionsextending into the propagation path of the pulse, varying dimensions ofa propagation pathway, and so on. Further, the keyboard device 500 mayinclude a combination of a plurality of the above tuning features in anattempt to alter the acoustic pulse characteristics. For example, thekeyboard 500 may include a projection tuning feature combined with arough texture on the surface of the projection to alter the acousticsignature of a particular tap on the surface 502 of the keyboard.

Another such tuning feature that may alter the acoustic pulse resultingfrom a tap on the surface of the keyboard device is one or more openingslocated along the propagation path of the acoustic pulse. FIG. 6 depictsa cross-sectional view similar to that shown in FIG. 3 of a keyboarddevice 600 utilizing acoustic pulse recognition to detect a tap on thekeyboard, including openings 640-644 on the surface 602 of the keyboardto distort or alter the resultant acoustic signature of the tap. FIG. 6Adepicts a cross-sectional top view similar to that shown in FIG. 3A ofthe same keyboard device 600 utilizing acoustic pulse recognition todetect a tap on the keyboard. Similar to the other tuning featuresdescribed above, the openings 640-644 may alter the acoustic signaturedetected by the piezo sensors 610-614 created by a tap on the topsurface 602 of the keyboard 600 by a user.

As described above, a tap on the surface 602 of the keyboard 600 createsan acoustic pulse 604, 606 that propagates away from the tapped area.One or more piezo sensors 610-614 located on or near the keyboardreceive the acoustic pulse which is then compared to one or moredatabases to determine the area that is tapped.

To alter or define the acoustic signature of a tap on the keyboardsurface 602, one or more openings may be located along the surfaces ofthe keyboard device 600. In the embodiment shown in FIG. 6, a firstopening 640 is located along the bottom surface of the keyboard on theleft side and a second opening 642 is located along the bottom surfaceof the keyboard on the right side. A third opening 644, as shown in FIG.6A, is also located along the bottom surface of the keyboard, near thefront of the keyboard device 600. Although three openings 640-644 areshown along the bottom surface of the device 600, the keyboard mayinclude any number of openings on any of the surfaces of the keyboard.Further, while the openings shown are generally circular in shape, theopenings may take any shape and size to alter or define the acousticpulse of a tap on the surface of the keyboard.

As mentioned, the openings 640-644 may alter the propagation andreflection of the acoustic pulse 604, 606 before it reaches the piezosensors 610, 612, altering the characteristics of the acoustic pulse.For example, the acoustic pulse 606 may split otherwise separate as itencounters the first opening 640 such that some of the pulse passes outof the opening and some of the pulse reaches the piezo sensor 610. Incontrast, acoustic pulse 606 is generally unaffected by the secondopening 642 as the acoustic pulse passes over the opening. In thismanner, the openings along the surface of the keyboard device 600 maycreate a phase encoding of the acoustic pulses 604, 606 as the pulsespropagate and reflect along the surfaces of the keyboard before reachingthe piezo sensors 610-614.

Upon receipt, the acoustic signatures detected by the piezo sensors610-614 of the keyboard 600 may be compared to a database of signaturesby the keyboard or an associated computing system to determine thelocation of the tap on the surface 602 of the keyboard. In thoseembodiments that include tuning features 640-644 designed to alter theacoustic pulses, a database may be maintained by the input device 600 orcomputing system that stores such altered acoustic signatures so thatthe received acoustic signatures are compared to the database of alteredacoustic signatures.

In addition, other environmental factors may also affect the acousticsignature of the taps along the surface of the keyboard device. Forexample, the user resting palms or other parts of the hand on thekeyboard device while typing may alter the acoustic signature of anyparticular tap. To account for the effect of the user resting his handson the keyboard device while typing, one or more pressure sensors may beincluded to detect pressure applied to the keyboard surface.

FIG. 7 depicts a cross-sectional view similar to that shown in FIG. 3 ofa keyboard device 700 utilizing a combination of piezoelectric sensors710, 712 to detect a tap on the keyboard surface and pressure sensors720, 722 to detect a dampening force applied to the keyboard surface702. FIG. 7A depicts a bottom view of the same keyboard device 700 todetect the presence of pressure on the surface of the keyboard that maydampen or alter the acoustic pulse of a tap on the keyboard surface. Thepressure sensors 720-728 included may be utilized to detect the presenceof a dampening force on the surface of the keyboard, as well as aid indetermining the area of the surface 702 that is tapped by the user ofthe keyboard device 700.

To detect the presence of a dampening force, such as a user resting hispalms on the surface 702 of the keyboard 700, one or more pressureswitches 720, 722 may be located along the bottom surface of thekeyboard. As shown in FIG. 7A, the pressure switches (720, 722, 726,728) may be located at the four corners of the bottom surface of thekeyboard device 700. However, it should be appreciated that the pressureswitches may be located anywhere on the keyboard device 700 that maydetect the presence of the dampening force. For example, pressure sensor724 of FIG. 7 is located just beneath the top surface 702 of the device700 to detect such a force. In general, the keyboard device 700 mayinclude any number of pressure sensors located in any position on thedevice to detect the presence of a dampening force on the surface of thekeyboard that may alter the acoustic signatures of a tap by the user.

In addition, pressure sensors 724 located just beneath the top surface702 of the keyboard device 700 may aid the device is pinpointing thelocation of a tap on the surface 702. This detection may be combinedwith other sensor detection, such as the detection of the acousticsignature and the capacitive detection described above, to accuratelylocate a tap on the surface 702 of the keyboard 700 by a user. Further,the pressure sensors 724 located just beneath the surface 702 of theinput device 700 may be configured to only detect and transmit a user'sinput if the pressure exerted exceeds a set threshold. Thus, if theinput provided does not provide enough pressure to the pressure sensor724, the input is not processed by the input device. In addition, thepressure sensors 724 may be programmed to detect different pressuresapplied to different segments of the input surface 702 to account forsome users pressing some keys harder than others.

The embodiment shown in FIGS. 7 and 7A may also utilize a plurality ofdatabases of acoustic signatures to compare a received acousticsignature against during operation of the keyboard 700. For example, thekeyboard 700 or computing system may maintain a first database thatstores a plurality of acoustic signatures for the device when nodampening force or pressure is applied to the device, other than the tapprovided by the user to indicate a keystroke. However, when a dampeningforce is detected by one or more of the pressure sensors 720-728, asecond database may be utilized that contains the acoustic signaturesfor the device in a damped configuration. Thus, the pressure sensors720-728 may aid the device in selecting the correct database to comparethe received acoustic signatures against to determine the location of akeystroke. Further, the detection of pressure on one pressure sensor butnot the other pressure sensors of the device may trigger the accessingof a third database.

The database of dampened acoustic signatures may be created in a similarfashion as the undamped database is created. In particular, a dampingforce may be applied to the device 700 during a calibration phase. Then,the top surface 702 may be tapped at discrete spatial intervals whilethe acoustic pulse received at the piezo sensors 710-714 is stored. Inthis manner, each dampened individual pulse signature is associated witha particular area of the keyboard device 700. Because it is known whichareas of the surface 702 of the keyboard 700 is associated with whichinput character, the unique damped acoustic signatures for each inputcharacter can be stored in a database accessible by the keyboard device700 or computing system. This database may be maintained separately andaccessed when the device detects a dampening pressure applied to thedevice 700. In an alternative embodiment, the dampened acousticsignature and undampened acoustic signature for each key of the keyboard700 may be maintained in the same database such that the correctsignature is accessed based on the environmental condition of thekeyboard.

Another environmental factor that may affect the acoustic signature of akeystroke on the keyboard device is ambient noise. As should beappreciated, adding noise to the acoustic pulse created by a tap on thesurface of the device likely changes the acoustic signature for thattap. Further, because the ambient noise for any particular environmentmay be difficult to anticipate, a database of the altered acousticsignatures for a device is similarly difficult to create. Therefore, inone embodiment, the input device may include a microphone situated topick up the ambient noise of the environment in an effort to providecanceling techniques to remove the ambient noise from the receivedacoustic signatures.

FIG. 8 depicts a top view of a keyboard device 800 utilizing amicrophone 802 to measure ambient noise around the keyboard to aid indetecting a tap on the surface of the keyboard. The embodiment of thekeyboard depicted in FIG. 8 is similar to the input devices describedabove, in that a tap performed by a user on the surface of the keyboardcreates a unique acoustic signature and detected by one or more piezosensors. However, ambient noise may alter the acoustic signature for oneor more taps such that the keyboard may be unable to determine thecorrect location of tap on the surface of the device.

To combat the altering of the acoustic signature by ambient noise, themicrophone 802 may be configured to detect the ambient noise and providea signal to the device 800 or associated computing system thatrepresents and mirrors the detected ambient noise. This signal may thenbe subtracted from the acoustic signatures detected by the piezo sensorsof the keyboard 800. Thus, by removing the ambient noise from thedetected acoustic signatures, the correct location of the keystroke onthe surface of the keyboard device 800 is determined.

In the configuration shown, the microphone 802 is located in the upperright-hand corner of the top surface of the keyboard 800. However, themicrophone 802 may be located anywhere on the keyboard that allows themicrophone to detect the ambient noise. In an alternate embodiment, themicrophone 802 may not located on the device itself, but may be locatedsomewhere near the device that allows the microphone to detect theambient noise. In general, the location of the microphone 802 does notdetract from the described embodiment. Further, while only onemicrophone 802 is shown in FIG. 8, the device 800 may include any numberof microphones or sound detecting sensors to collect a sample of theambient noise and perform noise canceling of the present ambient noisefrom the resulting acoustic signatures from a tap on the surface of thekeyboard device 800.

Yet another sensor may be included in the input keyboard device tofurther aid in locating the presence of a tap on the surface of thedevice. FIG. 9 depicts a cross-sectional view similar to that shown inFIG. 3 of a keyboard device utilizing a combination of piezoelectricsensors and proximity sensors to detect and locate a tap on the keyboardsurface. Similar to the embodiment described above with reference toFIG. 4, the proximity sensors 950, 952 may be combined with the acousticsignatures detected by the piezo sensors 910, 912 to detect a tap on thesurface 902 of the keyboard 900.

The proximity sensors 950, 952 may include one or more photosensorslocated along the edge of the keyboard device and corresponding infraredlight-emitting diodes (LEDs) oriented to create a grid on the keyboardand such that the photosensors receive the light projected from theLEDs. The presence of a object may be detected by the photosensors whenthe object interrupts the projected light. In this manner, when a userplaces a finger on the surface 902 of the device 900, the proximitysensors may detect the presence of that finger.

The proximity sensors 950, 952 may be used in junction with the piezosensors 910, 912 to provide an accurate determination of the location ofa tap by the user of the input keyboard 900 device. For example, thepiezo sensors 910, 912 may be used as described above to determine whicharea of the keyboard is tapped. However, in some instances, the exactlocation of the user's tap may not be obtained through the piezo sensors910, 912 alone. In these circumstances, the keyboard device 900 orassociated computing system may consult one or more proximity sensors950, 952 in an attempt to narrow the possible area of the user's tap toa specific area or key. In addition, the proximity sensors 950, 952 maybe utilized to activate and deactivate the keys or sensors of thekeyboard device 900 in response to placement of the user's finger near akey. For example, when a finger is not detected near a key, such keysmay be deactivated in the sense that such keys are removed from thepossible keys that may be pressed by the user. However, when a finger isdetected, those keys are activated. By removing some keys from thenumber of possible keys that are tapped by the user at any one time, thekeyboard 900 may determine the correct key tap at a faster rate.

FIG. 10 is a block diagram illustrating an exemplary computing systemthat may be used in implementing embodiments of the present disclosure.Further, the input devices described herein may include one or more ofthe described components to accomplish the described functions. Inaddition, the computing device and docking station may omit some of thedescribed components. The computer system (system) includes one or moreprocessors 1002-1006. Processors 1002-1006 may include one or moreinternal levels of cache (not shown) and a bus controller or businterface unit to direct interaction with the processor bus 1012.Processor bus 1012, also known as the host bus or the front side bus,may be used to couple the processors 1002-1006 with the system interface1014. System interface 1014 may be connected to the processor bus 1012to interface other components of the system 1000 with the processor bus1012. For example, system interface 1014 may include a memory controller1018 for interfacing a main memory 1016 with the processor bus 1012. Themain memory 1016 typically includes one or more memory cards and acontrol circuit (not shown). System interface 1014 may also include aninput/output (I/O) interface 1020 to interface one or more I/O bridgesor I/O devices with the processor bus 1012. One or more I/O controllersand/or I/O devices may be connected with the I/O bus 1026, such as I/Ocontroller 1028 and I/O device 1030, as illustrated.

I/O device 1030 may also include an input device (not shown), such as analphanumeric input device, including alphanumeric and other keys forcommunicating information and/or command selections to the processors1002-1006. Another type of user input device includes cursor control,such as a mouse, a trackball, or cursor direction keys for communicatingdirection information and command selections to the processors 1002-1006and for controlling cursor movement on the display device.

System 1000 may include a dynamic storage device, referred to as mainmemory 1016, or a random access memory (RAM) or other devices coupled tothe processor bus 1012 for storing information and instructions to beexecuted by the processors 1002-1006. Main memory 1016 also may be usedfor storing temporary variables or other intermediate information duringexecution of instructions by the processors 1002-1006. System 1000 mayinclude a read only memory (ROM) and/or other static storage devicecoupled to the processor bus 1012 for storing static information andinstructions for the processors 1002-1006. The system set forth in FIG.10 is but one possible example of a computer system that may employ orbe configured in accordance with aspects of the present disclosure.

According to one embodiment, the above techniques may be performed bycomputer system 1000 in response to processor 1004 executing one or moresequences of one or more instructions contained in main memory 1016.These instructions may be read into main memory 1016 from anothermachine-readable medium, such as a storage device. Execution of thesequences of instructions contained in main memory 1016 may causeprocessors 1002-1006 to perform the process steps described herein. Inalternative embodiments, circuitry may be used in place of or incombination with the software instructions. Thus, embodiments of thepresent disclosure may include both hardware and software components.

A machine readable medium includes any mechanism for storing informationin a form (e.g., software, processing application) readable by a machine(e.g., a computer). Such media may take the form of, but is not limitedto, non-volatile media and volatile media. Non-volatile media includesoptical or magnetic disks. Volatile media includes dynamic memory, suchas main memory 1016. Common forms of machine-readable medium mayinclude, but is not limited to, magnetic storage medium (e.g., floppydiskette); optical storage medium (e.g., CD-ROM); magneto-opticalstorage medium; read only memory (ROM); random access memory (RAM);erasable programmable memory (e.g., EPROM and EEPROM); flash memory; orother types of medium suitable for storing electronic instructions.

The foregoing merely illustrates certain principles and embodiments.Various modifications and alterations to the described embodiments willbe apparent to those skilled in the art in view of the teachings herein.It will thus be appreciated that those skilled in the art will be ableto devise numerous systems, arrangements and methods which, although notexplicitly shown or described herein, embody the principles of theembodiments and are thus within the spirit and scope of the presentdisclosure. From the above description and drawings, it will beunderstood by those of ordinary skill in the art that the particularembodiments shown and described are for purposes of illustrations onlyand are not intended to limit the scope of the present disclosure.References to details of particular embodiments are not intended tolimit the scope of the disclosure.

What is claimed is:
 1. A method for detecting a user input, comprising:detecting sound with a plurality of acoustic sensors in an electronicdevice, wherein the electronic device includes openings through which atleast some of the sound passes, and wherein detecting sound with theplurality of acoustic sensors comprises, with at least some of theacoustic sensors, detecting sound generated external to the electronicdevice; and with the electronic device, determining the location of theuser input on a surface at least partly using the detected sound thatwas generated external to the electronic device, wherein determining thelocation of the user input on the surface at least partly using thedetected sound that was generated external to the electronic devicecomprises: subtracting background noise from sound associated with theuser input.
 2. The method defined in claim 1 further comprising: withthe electronic device, determining the locations of a plurality ofadditional user inputs at least partly using the detected sound that wasgenerated external to the electronic device.
 3. The method defined inclaim 1 wherein the user input comprises an object touching the surfaceand wherein determining the location of the user input at least partlyusing the detected sound that was generated external to the electronicdevice comprises determining the location at which the object touchesthe surface.
 4. The method defined in claim 1 wherein each of theacoustic sensors comprises a microphone and wherein the user inputcorresponds to a letter.
 5. The method defined in claim 1 wherein eachof the acoustic sensors comprises a piezoelectric sensor.
 6. The methoddefined in claim 1 wherein determining the location of the user input atleast partly using the detected sound that was generated external to theelectronic device comprises determining the location of the user inputat least partly using at least one non-acoustic sensor in processing thesound detected with the plurality of acoustic sensors in determining thelocation of the user input.
 7. The method defined in claim 1 furthercomprising: determining whether a dampening force is applied to theelectronic device, wherein the dampening force is separate from the userinput and wherein determining the location of the user input at leastpartly using the detected sound that was generated external to theelectronic device comprises taking into account whether or not thedampening force is applied to the electronic device.
 8. A method fordetecting a user input, comprising: detecting sound with a plurality ofacoustic sensors in an electronic device, wherein the electronic deviceincludes openings through which at least some of the sound passes, andwherein detecting sound with the plurality of acoustic sensorscomprises, with at least one of the acoustic sensors, detecting soundgenerated separate from the electronic device; and with the electronicdevice, determining the location of the user input at least partly usingthe detected sound that was generated separate from the electronicdevice, wherein the user input comprises an object touching a surfaceand wherein determining the location of the user input at least partlyusing the detected sound that was generated separate from the electronicdevice comprises determining the location at which the object touchesthe surface.
 9. The method defined in claim 8 further comprising: withthe electronic device, determining the locations of a plurality ofadditional user inputs at least partly using the detected sound that wasgenerated separate from the electronic device.
 10. An electronic devicecomprising: a plurality of acoustic sensors, wherein at least one of theplurality of acoustic sensors detects sound generated external to theelectronic device, wherein the detected sound is not generated from auser touching the electronic device; a plurality of acoustic openingsthrough which at least some of the sound passes; and circuitry thatdetermines a location on a surface at which a sound-generating userinput to the electronic device is provided at least partly using thedetected sound that was generated external to the electronic device. 11.The electronic device defined in claim 10 wherein at least two of theplurality of acoustic sensors detect sound generated external to theelectronic device.
 12. The electronic device defined in claim 10 furthercomprising: at least one non-acoustic sensor, wherein the circuitrydetermines the location of the sound-generating user input by at leastpartly using the non-acoustic sensor in processing the sound detectedwith the plurality of acoustic sensors.
 13. The electronic devicedefined in claim 10 wherein the electronic device comprises atouch-screen.
 14. The electronic device defined in claim 10 wherein theelectronic device is a tablet.
 15. The electronic device defined inclaim 10 wherein the electronic device is a computing device.
 16. Theelectronic device defined in claim 10 wherein the electronic device is amobile computing device.
 17. The electronic device defined in claim 10wherein the electronic device is a computer.
 18. The electronic devicedefined in claim 10 further comprising: one or more tuning features thatalter the sound of the sound-generating user input prior to detection bythe plurality of acoustic sensors.
 19. The electronic device defined inclaim 18 wherein the one or more tuning features comprise one or moreopenings in the electronic device.